1. Field of the Invention
The invention relates track laying vehicles, and more particularly to an electromechanical drive for track-laying vehicles.
2. Description of the Related Art
It is known that electric drives for track-laying vehicles, compared with conventional, fully automatic, hydromechanical power-shift transmissions, permit increased flexibility in the component arrangement as well as a more favorable energy management of the vehicle with infinitely variable traction drive. The high demands made on the traction motor and on the power electronics in purely electric drives-without mechanical shift stages-leads to electric motors of large diameters. These motors require a lot of construction space and can only be arranged in vehicles to a limited extent.
Avoiding these disadvantages has led to the development of electromechanical drives. German Patent No. 37 28 171 C2 shows an electromechanical drive block which has an electric motor for the traction drive (traction motor), which is connected in each case to track drive sprockets via differential gear units. The effort of construction of the electric traction drive is drastically reduced by the interposition of a 2-speed gear unit. For the regenerative steering, however, a further electric motor (steering motor) and a mechanical zero shaft which transmit the mechanical output from the one to the other drive side, are necessary. The controlled supply of energy to both electric motors (traction and steering motors) is effected in a purely electrical manner via a generator driven by an internal combustion engine.
An object of the present invention is to provide a more highly integral, more compact drive which retains the aforementioned advantages.
This and other objects are achieved in accordance with of invention by the realization of a comparatively short overall length of the drive unit by the coaxial arrangement of a plurality of components in the same plane, and by the integration of further elements in the interior space of the rotor of an electric motor.
Due to the mechanical gear stages, it is possible to revert to electric motors which have a smaller output and a substantially smaller diameter. As a result, it is possible, for example, to coaxially drive a side transmission gear of the track drive sprocket attached to the rear hull end of the vehicle. As a result, an additional gear unit for compensating for axial misalignment may be dispensed with.
On account of the short installation length, an access opening, for example, may be provided for the free space between the two drives.
Since the friction brake is arranged of the outside on the output shaft, the braking power which is required by the tracks is absorbed directly and the brake can easily be cooled by ambient air. A further advantage of this arrangement is the ease of maintenance of the brake. The construction of the drive unit permits both electrical and mechanical-hydraulic actuation of the friction brake and of the clutches for the gear-change operations. When travelling around curves, motors on the inside of the curve work as generators, which supply energy to the motors on the outside of the curve via power electronics, as a result of which regenerative steering is possible. The flexibility of the arrangement of the drive components compared with the prior art is further increased in an advantageous manner by the invention.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.